Table 3.
Association of Anopheles funestus densities with different IRS insecticides supplementing LLINs upon months before, during and when not spraying
| Indoor residual spraying insecticide treatment regimen | Absolute numbers caught | Mean catchesa | Relative biting rates of An. funestus | |
|---|---|---|---|---|
| [95 % Confidence interval (CI)] | (RR)a [95 % CI] | P value | ||
| Deltamethrin WG) | ||||
| 1–3 months since last spray | 73 | 0.112 [0.641, 0.371] | 0.99 [0.63, 1.56] | 0.897 |
| 4–6 months since last spray | 1229 | 0.641 [0.371, 1.109] | 3.98 [3.15, 5.04] | <0.001 |
| 7–12 months since last spray | 134 | 0.111 [0.062, 0.199] | 0.86 [0.64, 1.17] | 0.067 |
| >12 months since last spray or never | 1186 | 0.189 [0.113, 0.317] | 1 [NA]b | NAb |
| Lambdacyhalothrin CS | ||||
| 1–3 months since last spray | 20 | 0.191 [0.090, 0.405] | 1.03 [0.56, 1.88] | 0.805 |
| 4–6 months since last spray | 6 | 0.055 [0.022, 0.141] | 0.17 [0.08, 0.39] | <0.001 |
| 7–12 months since last spray | 0 | NEc | NEc | 0.972 |
| >12 months since last spray or never | 182 | 0.198 [0.121] | 1 [NA]b | NAb |
| Pirimiphosmethyl EC | ||||
| 1–3 months since last spray | 478 | 0.234 [0.131, 0.417] | 1.04 [0.83, 1.30] | 0.786 |
| 4–6 months since last spray | 346 | 0.055 [0.030, 0.098] | 0.25 [0.20, 0.33] | <0.001 |
| 7–12 months since last spray | 160 | 0.159 [0.086, 0.293] | 0.69 [0.50, 0.95] | 0.151 |
| >12 months since last spray or never | 2823 | 0.234 [0.131, 0.417] | 1 [NA]b | NAb |
| Pirimiphosmethyl CS | ||||
| 1–3 months since last spray | 14 | 0.021 [0.009, 0.047] | 0.07 [0.04, 0.13] | <0.001 |
| 4–6 months since last spray | 70 | 0.004 [0.002, 0.008] | 0.02 [0.01, 0.02] | <0.001 |
| 7–12 months since last spray | NEc | NEc | NEc | NEc |
| >12 months since last spray or never | 2087 | 0.253 [0.152, 0.422] | 1 [NA]b | NA |
NA Not applicable because reference group, NE Not estimable because no spraying of this insecticide regimen was conducted early enough to yield impact data beyond 6 months post-spray but before the following spray round so no data are available for estimation
aThe effect of different IRS treatment regimens on the mean catches of An. funestus species where estimated by fitting generalized linear mixed models (GLMMs) with An. funestus catches treated as dependent variables. The households where nested within villages which were also nested within the clusters, these together with date were treated as random effects, while the different IRS treatment regimens were categorized as independent variables. A Poisson distribution with no intercept was used to estimate the mean catches while an intercept was included in estimating the RR